SOIL AMENDMENT EFFECTS ON WATERMELON YIELD AND QUALITY
William Terry Kelley
Extension Horticulturist
University of Georgia
P.O. Box 1209
Tifton, GA 31793
wtkelley@uga.edu
Introduction
Watermelons are annually Georgia’s largest vegetable commodity based on
acreage. Production usually exceeds 30,000 acres and in 2004 the crop had a farm gate
value of over $85 million. Development of a good canopy to protect fruit and overall
yield of high quality melons are primary concerns of Georgia watermelon growers.
Horizon Ag Products and Helena Chemical Company have three new products with
potential to increase watermelon yield. Hydra-Hume is a humic acid product which is
purported to have the ability to increase uptake of micronutrients. Es-Cal-Eight is a low
pH material with 5% nitrogen and 8% calcium. QHP is a combination of amino acids,
organic acids and carbohydrates that “works by shifting the energy priority to the fruiting
side of the vegetative/fruit demand balance”. These materials alone and in combination
were tested to determine their effects on yield and quality of watermelon.
Methods
Watermelon plants (variety “Tri-X 313”, Syngenta Seed Co.) were produced in a
greenhouse by a commercial transplant grower. Plots were established at the Coastal
Plain Experiment Station Tifton Vegetable Park (elev. 382 feet) in Tifton, GA. Plot land
was deep turned and disced and 600 lb/A 10-10-10 was applied and incorporated. Methyl
bromide was applied (134 lb. a.i./acre) when black plastic mulch and drip tape were
installed.
Watermelons were transplanted on April 19, 2005 into a Tifton sandy loam (fineloamy siliceous thermic Plinthic Kandiudults) soil. Plots consisted of one row of
watermelons planted on raised beds spaced six feet apart (from center to center). In-row
spacing was 48 inches per plant. Plots were each 25 feet long and were replicated four
times. The experiment was arranged in a Randomized Complete Block Design.
Hydra-Hume was injected at one gallon per acre shortly after planting. Es-CalEight was injected at one gallon per acre one week prior to bloom and every three weeks
thereafter. Injection dates for Es-Cal-Eight were May 24, June 14 and July 6, 2005. QHP
was injected at 1.5 pounds per application beginning at first flower and approximately
every four weeks thereafter. Those treatments were applied on May 31 and June 28, 2005.
A total of 150 pounds N was applied, 60 pounds of P and approximately 100 pounds of K
All but the pre-plant fertilizer was applied through the drip irrigation system.
Watermelons were harvested on July 7, July 12 and July 19, 2005 and data collected on
yield and quality. Other than fertilizers, normal cultural and pest control practices were
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used. Data were analyzed with the Statistical Analysis System and means separated with
Least Significant Difference.
Results and Discussion
Results are presented in Table 1. There were no significant differences among
treatments for fruit number or fruit weight per acre. Plots treated with Hydra-Hume had a
tendency to produce more fruit than the untreated or any other treatment. Only the twoway combinations with Hydra-Hume and the other two chemicals produced greater fruit
weight than the untreated check. It might also be worth noting that the tissue analysis for
Ca revealed that the highest Ca levels were seen where either Hydra-Hume or Es-CalEight was used. There were no meaningful significant differences in this test. While some
treatments appeared to be better than the untreated, others were not. In this particular test
it is reasonable to conclude that none of the treatments had any remarkable effect on
marketable yield of watermelons over the untreated check.
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Table 1.
Fruit number per acre, yield per acre, average fruit weight and tissue analysis results combined across
replications for watermelons treated with various combinations of Hydra-Hume, QHP and Es-Cal-8 and
untreated watermelons at Tifton, Georgia in 2005.
Fruit/A
Weight/A
Avg Fruit
(No.)
(Lbs.)
(Lbs.)
Untreated
1286 a
25486 a
20.0a
2.87
0.23
1.22
0.64
4.07
0.22
54
22
Hydra-Hume
1362 a
23814 a
17.4abc
2.76
0.17
1.18
0.73
4.91
0.20
73
Es-Cal-8
1286 a
20646 a
15.9c
2.77
0.21
1.21
0.74
4.72
0.30
HH + EC8
1437 a
27036 a
19.1ab
2.49
0.20
1.18
0.86
6.00
QHP
1135 a
18838 a
16.7bc
2.87
0.23
1.16
0.66
HH + QHP
1664 a
32353 a
19.1ab
3.01
0.24
1.24
QHP + EC8
1135 a
19557 a
17.9abc
2.90
0.25
HH + QHP + EC8
1211 a
21985 a
18.3abc
2.35
0.19
Mean of Test
1314
23714
18.0
L.S.D. (0.05)
925.4
16373
2.8
Treatment
N
P
K
Mg
Ca
S
B
Zn
Fe
Cu
117
65
7
19
132
55
7
86
24
161
61
8
0.21
87
25
164
68
7
3.88
0.23
71
23
132
73
7
0.67
4.24
0.25
61
24
167
58
11
1.07
0.70
4.57
0.22
72
24
163
56
9
1.23
0.68
4.75
0.20
73
21
156
54
8
(%)
(ppm)
C.V. (%)
47.9
47.0
10.5
Plots consisted of a single row with one row per bed and six plants per row spaced 48 inches apart.
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Mn